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15
Mil
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Photo: Bill and Melinda Gates Foundation
15
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Photo: Bill and Melinda Gates Foundation/ /John Ahern
172 15 m
illion PrEtErm
BirthS: PrioritiES fo
r action BaSEd o
n natio
nal, rEgio
nal an
d gloBal EStim
atES
— Hannah Blencowe, Simon Cousens, Doris Chou, Mikkel Z Oestergaard, Lale Say, Ann-Beth Moller, Mary Kinney, Joy Lawn
Chapter 2.15 million preterm births:
priorities for action based on national, regional and global estimates
172 15 m
illion PrEtErm
BirthS: PrioritiES fo
r action BaSEd o
n natio
nal, rEgio
nal an
d gloBal EStim
atES
Table 2.1: Long-term impact of preterm birth on survivors
Long-term out-comes
Examples: Frequency in survivors:
Specific physical effects
Visual impairment •Blindness or high myopia after retinopathy of prematurity
•Increased hypermetropia and myopia
Around 25% of all extremely preterm affected [a]Also risk in moderately preterm babies especially if poorly monitored oxygen therapy
Hearing impairment Up to 5 to 10% of extremely preterm [b]
Chronic lung disease of prematurity
•From reduced exercise tolerance to requirement for home oxygen
Up to 40% of extremely preterm [c]
Long-term cardiovascular ill-health and non- communicable disease
•Increased blood pressure•Reduced lung function•Increased rates of asthma •Growth failure in infancy, accelerated weight gain
in adolescence
Full extent of burden still to be quantified
Neuro-developmental/ behavioral effectse
Mild Disorders of executive functioning
•Specific learning impairments, dyslexia, reduced academic achievement
Moderate to severe Global developmental delay
•Moderate/severe cognitive impairment•Motor impairment•Cerebral palsy
Affected by gestational age and quality of care dependent [f]
Psychiatric/ behavioral sequelae
•Attention deficit hyperactivity disorder•Increased anxiety and depression
Family, economic and societal effects
Impact on familyImpact on health serviceIntergenerational
•Psychosocial, emotional and economic•Cost of care [h] – acute, and ongoing•Risk of preterm birth in offspring
Common varying with medical risk factors, disability, socioeconomic status [g]
References: a O’Connor et al. (2007). “Ophthalmological problems associated with preterm birth.” Eye (Lond) 21(10): 1254-1260.b Marlow et al. (2005). “Neurologic and developmental disability at six years of age after extremely preterm birth.” N Engl J Med 352(1): 9-19., Doyle et al (2001). “Outcome at 5 years of age of children 23 to 27 weeks’ gestation: refining the prognosis.” Pediatrics 108(1): 134-141.c Greenough, A. (2012). “Long term respiratory outcomes of very premature birth (<32 weeks).” Semin Fetal Neonatal Med 17(2): 73-76.d Doyle et al. (2003). “Health and hospitalistions after discharge in extremely low birth weight infants.” Semin Neonatol 8(2): 137-145., Escobar, G. J., R. H. Clark et al. (2006). “Short-term outcomes of infants born at 35 and 36 weeks gestation: we need to ask more questions.” Semin Perinatol 30(1): 28-33.e Mwaniki et al., Long-term neurodevelopmental outcomes after intrauterine and neonatal insults: a systematic review. Lancet, 2012.f Hagberg et al. (2001). “Changing panorama of cerebral palsy in Sweden. VIII. Prevalence and origin in the birth year period 1991-94.” Acta Paediatr 90(3): 271-277.Doyle et al (2001). “Outcome at 5 years of age of children 23 to 27 weeks’ gestation: refining the prognosis.” Pediatrics 108(1): 134-141.g Singer et al. (1999). “Maternal psychological distress and parenting stress after the birth of a very low-birth-weight infant.” JAMA 281(9): 799-805.Moore M., H. Gerry Taylor et al. (2006). “Longitudinal changes in family outcomes of very low birth weight.” J Pediatr Psychol 31(10): 1024-1035.h Institute of Medicine of the National Academies (2006). “Preterm Birth: Causes, Consequences, and Prevention.” from http://www.iom.edu/Reports/2006/Preterm-Birth-Causes-Consequences-and-Prevention.aspx
Why focus on preterm birth?Preterm birth is a major cause of death and a significant
cause of long-term loss of human potential amongst
survivors all around the world. Complications of preterm
birth are the single largest direct cause of neonatal deaths,
responsible for 35% of the world’s 3.1 million deaths a year,
and the second most common cause of under-5 deaths
after pneumonia (Figure 2.1). In almost all high- and middle-
income countries of the world, preterm birth is the leading
cause of child death (Liu et al., 2012). Being born preterm
also increases a baby’s risk of dying due to other causes,
especially from neonatal infections (Lawn et al., 2005) with
preterm birth estimated to be a risk factor in at least 50%
of all neonatal deaths (Lawn et al., 2010).
Addressing preterm birth is essential for accelerating prog-
ress towards Millennium Development Goal 4 (see Chapter
1) (UN, 2011; Valea et al., 1990). In addition to its significant
contribution to mortality, the effect of preterm birth amongst
some survivors may continue throughout life, impairing
neurodevelopmental functioning through increasing the risk
of cerebral palsy, learning impairment and visual disorders
and affecting long-term physical health with a higher risk of
non-communicable disease (Rogers and Velten, 2011). These
effects exert a heavy burden on families, society and the
health system (Table 2.1) (Institute of Medicine, 2007). Hence,
preterm birth is one the largest single conditions in the Global
Burden of Disease analysis given the high mortality and the
considerable risk of lifelong impairment (WHO, 2008).
The Global Action Report on Preterm Birth18
Routine data on preterm birth rates are not collected in many
countries and, where available, are frequently not reported
using a standard international definition. Time series using
consistent definitions are lacking for all but a few countries,
making comparison within and between countries challeng-
ing. In high-income countries with reliable data, despite
several decades of efforts, preterm birth rates appear to
have increased from 1990 to 2010 (Joseph, 2007; Langhoff-
Roos et al., 2006; Martin et al., 2010; Thompson et al., 2006),
although the United States reports a slight decrease in the
rates of late preterm birth (34 to <37 completed weeks) since
2007 (Martin et al., 2011).
There has been limited assessment of the size of the burden
of preterm birth globally. Previous global level estimates of
preterm birth published by WHO suggested that in 2005, 13
million babies were born too soon, 10% of babies worldwide
(Beck et al., 2010).
This chapter presents new data from the first set of esti-
mates of preterm birth rates (all live births before 37 com-
pleted weeks) for 184 countries in 2010 and a time series
Preterm birth complications
1.08 million
Preterm birth is a DIRECT
cause of 35% of all neonatal
deaths
Intrapartum-related
0.72 million
Neonatal infections
0.83 million
Other neonatal
conditions 181,000 Congenital
abnormalities 270,000
Preterm birth is a risk factor for neonatal and postneonatal deathsAt least 50% of all neonatal deaths are preterm
INDIRECT Moderate and late preterm
birth increase the chance of
dying from infections
Figure 2.1: Estimated distribution of causes of 3.1 million neonatal deaths in 193 countries in 2010
Source: Updated from Lawn et al., 2005, using data from 2010 published in Liu Let al., 2012.
Source: Adapted from Blencowe et al. National, regional and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implicationsWorld Bank income groupings: HIC=High-Income Countries LMIC=Low and Middle Income available from http://data.worldbank.org/about/country-classifications/country-and-lending-groups
34 weeks:50% chance of survival in manyLMIC countries
BORN TOO SOON
PREGNANCY
First Trimester Second Trimester Third TrimesterMonths // 4 5 6 7 8 9 10
BORN ALIVE
BORN DEAD
Miscarriage Stillbirths
Stillbirth international comparison definition (WHO)Birthweight ≥ 1000 gms
or ≥ 28 weeks completed gestation
Preterm birth (<37 weeks gestation) Term Post-term
37 - <42weeks
42 weeksor more
Extremely preterm<28 weeks
Verypreterm28 - <32weeks
Moderate or Late preterm
32 - <37weeks
Differing lower cut off forstillbirth definition
from 18 to 28 weeks
Differing lower cut off forpreterm birth definition
from 20 to 28 weeks
Early definition (ICD)Birthweight ≥ 500 gms
or ≥ 22 weeks completed gestation
22weeks
28weeks
24 weeks:50% chance of
survival with neonatalintensive care
(most HIC countries)
Viability
TOTAL BURDEN OF PRETERM BIRTH
Figure 2.2: Overview of definitions for preterm birth and related pregnancy outcomes
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for 65 countries with sufficient data (Blencowe et al., 2012).
Additionally, we estimate three preterm subgroups useful for
public health planning (Blencowe et al., 2012). The chapter
also presents the key risk factors for preterm births, and
makes recommendations for efforts to improve the data and
use the data for action to address preterm birth.
Understanding the data
Preterm birth — what is it?
Defining preterm birthPreterm birth is defined by WHO as all births before 37
completed weeks of gestation or fewer than 259 days since
the first day of a woman’s last menstrual period (WHO,
1977). Preterm birth can be further sub-divided based
on gestational age: extremely preterm (<28 weeks), very
preterm (28 - <32 weeks) and moderate preterm (32 - <37
completed weeks of gestation) (Figure 2.2). Moderate
preterm birth may be further split to focus on late preterm
birth (34 - <37 completed weeks).
The international definition for stillbirth rate clearly states to
use stillbirths > 1,000 g or 28 weeks gestation, improving
the ability to compare rates across countries and times
(Cousens et al., 2011; Lawn et al., 2011). For preterm birth,
International Classification of Disease (ICD) encourages
the inclusion of all live births. This definition has no lower
boundary, which complicates the comparison of reported
rates both between countries and within countries over time
since perceptions of viability of extremely preterm babies
change with increasingly sophisticated neonatal intensive
care. In addition, some reports use non-standard cut-offs
for upper gestational age (e.g., including babies born at up
to 38 completed weeks of gestation).
In some high- and middle-income countries, the official defi-
nitions of live birth or stillbirth have changed over time. Even
without an explicit lower gestational age cut-off in national
definitions, the medical care given and whether or not birth and
death registration occurs may depend on these perceptions of
viability (Goldenberg et al., 1982; Sanders et al., 1998). Hence,
even if no “official” lower gestational age cut-off is specified for
recording a live birth, misclassification of a livebirth to stillbirth
is more common if the medical team perceives the baby to
be extremely preterm and thus less likely to survive (Sanders
et al., 1998). Eighty percent of all stillbirths in high-income
countries are born preterm, accounting for 5% of all preterm
births. Counting only live births underestimates the true burden
of preterm birth (Flenady et al., 2011; Kramer et al., 2012).
In addition to the definition and perceived viability issue,
some reports include only singleton live births, complicating
comparison even further. From a public health perspective
and for the purposes of policy and planning, the total number
of preterm births is the measure of interest. Some countries
only include live births after a specific cut-off, for example,
22 weeks. Given the limited accuracy of gestational age
assessment, the upper limit of 37 completed weeks should
be the standard for all studies (Zhang and Kramer, 2009).
For the purpose of this report and its estimates, the following
definition of preterm birth rate is used:
All live births before 37 completed weeks (whether
singleton or multiple)
Per 100 live births
DEFINITION OF PRETERM BIRTH RATE
Photo: March of Dimes
The Global Action Report on Preterm Birth20
Preterm birth – why does it occur?Preterm birth is a syndrome with a variety of causes which
can be classified into two broad subtypes: (1) spontane-
ous preterm birth (spontaneous onset of labor or following
prelabor premature rupture of membranes (pPROM)) and
(2) provider-initiated preterm birth (defined as induction of
labor or elective caesarian birth before 37 completed weeks
of gestation for maternal or fetal indications (both “urgent”
or “discretionary”), or other non-medical reasons) (Table
2.2) (Goldenberg et al., 2012).
Spontaneous preterm birth is a multi-factorial process,
resulting from the interplay of factors causing the uterus to
change from quiescence to active contractions and to birth
before 37 completed weeks of gestation. The precursors to
spontaneous preterm birth vary by gestational age (Steer,
2005), and social and environmental factors, but the cause
of spontaneous preterm labor remains unidentified in up to
half of all cases (Menon, 2008). Maternal history of preterm
birth is a strong risk factor and most likely driven by the
interaction of genetic, epigenetic and environmental risk
factors (Plunkett and Muglia, 2008). Many maternal factors
have been associated with an increased risk of spontaneous
preterm birth, including young or advanced maternal age,
short inter-pregnancy intervals and low maternal body mass
index (Goldenberg et al., 2008; Muglia and Katz, 2010).
Another important risk factor is uterine over distension with
multiple pregnancy. Multiple pregnancies (twins, triplets, etc.)
carry nearly 10 times the risk of preterm birth compared to
singleton births (Blondel et al., 2006). Naturally occurring
multiple pregnancies vary among ethnic groups with reported
rates from 1 in 40 in West Africa to 1 in 200 in Japan, but a
large contributor to the incidence of multiple pregnancies has
been rising maternal age and the increasing availability of
assisted conception in high-income countries (Felberbaum,
2007). This has led to a large increase in the number of births
of twins and triplets in many of these countries. For example,
England and Wales, France and the United States reported 50
to 60% increases in the twin rate from the mid-1970s to 1998,
with some countries (e.g.
Republic of Korea) report-
ing even larger increases
(Blondel and Kaminski,
2002). More recent poli-
cies, limiting the number of
embryos transferred during
in vitro fertilization may
have begun to reverse this
trend in some countries,
(Kaprio, 2005) while others
continue to report increas-
ing multiple birth rates (Lim,
2011; Martin et al., 2010).
Infection plays an impor-
tant role in preterm birth.
Urinary tract infections,
malaria, bacterial vagino-
sis, HIV and syphilis are all
associated with increased
r i s k o f p r e te r m b i r t h
(Gravett et al., 2010). In
Table 2.2: Types of preterm birth and risk factors
Type: Risk Factors: Examples: Interventions:
Spontaneous preterm birth:
Age at pregnancy and pregnancy spacing
Adolescent pregnancy, advanced maternal age, or short inter-pregnancy interval
Preconception care, including encouraging family planning beginning in adolescence and continuing between pregnancies (see Chapter 3)
Multiple pregnancy Increased rates of twin and higher order pregnancies with assisted reproduction
Introduction and monitoring of policies for best practice in assisted reproduction
Infection Urinary tract infections, malaria, HIV, syphilis, bacterial vaginosis,
Sexual health programs aimed at prevention and treatment of infections prior to pregnancy. Specific interventions to prevent infections and mechanisms for early detection and treatment of infections occurring during pregnancy. (see Chapters 3 and 4)
Underlying maternal chronic medical conditions
Diabetes, hypertension, anaemia, asthma, thyroid disease
Improve control prior to conception and throughout pregnancy (see Chapters 3 and 4)
Nutritional Undernutrition, obesity, micronutrient deficiencies
(see Chapters 3 and 4)
Lifestyle/work related
Smoking, excess alcohol consumption, recreational drug use, excess physical work/activity
Behavior and community interventions targeting all women of childbearing age in general and for pregnant women in particular through antenatal care with early detection and treatment of pregnancy complications (see Chapters 3 and 4)
Maternal psychological health
Depression, violence against women
(see Chapters 3 and 4)
Genetic and other Genetic risk, e.g., family historyCervical incompetence
Provider-initiated preterm birth:
Medical induction or cesarean birth for:obstetric indicationFetal indication
Other - Not medically indicated
There is an overlap for indicated provider-initiated preterm birth with the risk factors for spontaneous preterm birth
In addition to the above: Programs and policies to reduce the practice of non-medically indicated cesarean birth(Chapter 4)
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addition, other conditions have more recently been shown
to be associated with infection, e.g., “cervical insufficiency”
resulting from ascending intrauterine infection and inflam-
mation with secondary premature cervical shortening (Lee
et al., 2008).
Some lifestyle factors that contribute to spontaneous
preterm birth include stress and excessive physical
work or long times spent standing (Muglia and Katz,
2010). Smoking and excessive alcohol consumption as
well as periodontal disease also have been associated
with increased risk of preterm birth (Gravett et al., 2010).
Preterm birth is both more com-
mon in boys, with around 55%
of all preterm births occurring in
males (Zeitlin, 2002), and is asso-
ciated with a higher risk of dying
when compared to girls born at a
similar gestation (Kent 2012).
The role of ethnicity in preterm
birth (other than through twinning
rates) has been widely debated,
but evidence supporting a varia-
tion in normal gestational length
with ethnic group has been
reported in many population-
based studies since the 1970s
(Ananth and Vintzileos, 2006).
While this variation has been
linked to socioeconomic and lifestyle factors in some stud-
ies, recent studies suggest a role for genetics. For example,
babies of black African ancestry tend to be born earlier than
Caucasian babies (Steer, 2005; Patel et al., 2004). However,
for a given gestational age, babies of black African ancestry
have less respiratory distress (Farrell and Wood, 1976), lower
neonatal mortality (Alexander et al., 2003) and are less likely
to require special care than Caucasian babies (Steer, 2005).
Babies with congenital abnormalities are more likely to be
born preterm, but are frequently excluded from studies
reporting preterm birth rates. Few national-level data on the
prevalence of the risk factors for preterm birth are available
for modeling preterm birth rates.
The number and causes of provider-initiated preterm birth
are more variable. Globally, the highest burden countries
have very low levels due to lower coverage of pregnancy
monitoring and low cesarean birth rates (less than 5% in
most African countries). However, in a recent study in the
United States, more than half of all provider-initiated pre-
term births at 34 to 36 weeks gestation were carried out in
absence of a strong medical indication (Gyamfi-Bannerman
et al., 2011). Unintended preterm birth also can occur with
the elective delivery of a baby thought to be term due to
errors in gestational age assessment (Mukhopadhaya
and Arulkumaran, 2007). Clinical conditions underlying
medically-indicated preterm birth can be divided into
maternal and fetal of which severe
pre-eclampsia, placental abrup-
tion, uterine rupture, cholestasis,
fetal distress and fetal growth
restriction with abnormal tests
are some of the more important
direct causes recognized (Ananth
and Vintzileos, 2006). Underlying
maternal conditions (e.g., renal
disease, hypertension, obesity
and diabetes) increase the risk
of maternal complications (e.g.,
pre-eclampsia) and medically-indi-
cated preterm birth. The worldwide
epidemic of obesity and diabetes
is, thus, l ike ly to become an
increasingly important contributor
to global preterm birth. In one region in the United Kingdom,
17% of all babies born to diabetic mothers were preterm,
more than double the rate in the general population (Steer,
2005). Both maternal and fetal factors are more frequently
seen in pregnancies occurring after assisted fertility treat-
ments, thus increasing the risk of both spontaneous and
provider-initiated preterm births (Kalra and Molinaro, 2008;
Mukhopadhaya and Arulkumaran, 2007).
Differentiating the causes of preterm birth is particularly
important in countries where cesarean birth is common.
Nearly 40% of preterm births in France and the United
States were reported to be provider-initiated in 2000,
Photo: Joshua Roberts/Save the Children
The Global Action Report on Preterm Birth22
compared to just over 20% in Scotland and the Netherlands.
The levels of provider-initiated preterm births are increasing
in all these countries in part due to more aggressive policies
for caesarean section for poor fetal growth (Joseph et al.,
1998, 2002). In the United States, this increase is reported
to be at least in part responsible for the overall increase in
the preterm birth rate from 1990 to 2007 and the decline
in perinatal mortality (Ananth and Vintzileos, 2006). No
population-based studies are available from low- or middle-
income countries. However, of the babies born preterm in
tertiary facilities in low- and middle-income countries, the
reported proportion of preterm births that were provider-
initiated ranged from around 20% in Sudan and Thailand to
nearly 40% in 51 facilities in Latin America and a teaching
hospital in Ghana (Barros and Velez Mdel, 2006; Alhaj et
al., 2010; Ip et al., 2010; Nkyekyer et al., 2006). However,
provider-initiated preterm births will represent a relatively
smaller proportion of all preterm births in these countries
where access to diagnostic tools is limited. These pregnan-
cies, if not delivered electively, will follow their natural his-
tory, and may frequently end in spontaneous preterm birth
(live or stillbirth) (Klebanoff and Shiono, 1995).
Preterm birth — how is it measured?There are many challenges to measuring preterm birth
rates that have inhibited national data interpretation and
multi-country assessment. In addition to the variable
application of the definition, the varying methods used
to measure gestational age and the differences in case
ascertainment and registration complicate the interpre-
tation of preterm birth rates across and within nations.
Assessing gestational ageMeasurement of gestational age has changed over time.
As the dominant effect of gestational age on survival and
long-term impairment has become apparent over the last 30
years, perinatal epidemiology has shifted from measuring
birthweight alone to focusing on gestational age. However,
many studies, even of related pregnancy outcomes, con-
tinue to omit key measures of gestational age. The most
accurate “gold standard” for assessment is routine early
ultrasound assessment together with fetal measurements,
ideally in the first trimester. Gestational assessment based
on the date of last menstrual period (LMP) was previously
the most widespread method used and remains the only
available method in many settings. It assumes that concep-
tion occurs on the same day as ovulation (14 days after the
onset of the LMP). It has low accuracy due to considerable
variation in length of menstrual cycle among women, con-
ception occurring up to several days after ovulation and the
recall of the date of LMP being subject to errors (Kramer et
al., 1988). Many countries now use “best obstetric estimate,”
combining ultrasound and LMP as an approach to estimate
gestational age. The algorithm used can have a large impact
on the number of preterm births reported. For example,
a large study from a Canadian teaching hospital found
a preterm rate of 9.1% when assessed using ultrasound
alone, compared to 7.8% when using LMP and ultrasound
(Blondel et al., 2002).
Any method using ultrasound requires skilled technicians,
equipment and for maximum accuracy, first-trimester
antenatal clinic attendance. These are not common
in low-income settings where the majority of preterm
births occur. Alternative approaches to LMP in these
settings include clinical assessment of the newborn
after birth, fundal height or birthweight as a surrogate.
Pho
to: M
icha
el B
isce
glie
/Sav
e th
e C
hild
ren
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While birthweight is closely linked with gestational age,
it cannot be used interchangeably since there is a range
of “normal” birthweight for a given gestational age and
gender. Birthweight is likely to overestimate preterm birth
rates in some settings, especially in South Asia where a
high proportion of babies are small for gestational age.
Accounting for all birthsThe recording of births and deaths and the likelihood
of active medical intervention after preterm birth are
affected by perceptions of viability and social and eco-
nomic factors, especially in those born close to the lower
gestational age cut-off used for registration. Any baby
showing signs of being live at birth should be registered
as a livebirth regardless of the gestation (WHO, 2004).
The registration thresholds for stillbirths vary between
countries from 16 to 28 weeks, and under-registration of
both live and stillbirths close to the registration boundary
is well documented (Froen et al., 2009). The cut-off for
viability has changed over time and varies across settings,
with babies born at 22 to 24 weeks receiving full intensive
care and surviving in some high-income countries, whilst
babies born at up to 32 weeks gestation are perceived as
non-viable in many low-resource settings. An example of
this reporting bias is seen in high-income settings where
the increase in numbers of extremely preterm (<28 weeks)
births registered is likely to be due to improved case
ascertainment rather than a genuine increase in preterm
births in this group (Consultative Council on Obstetric
and Paediatric Mortality and Morbidity, 2001) and three
community cohorts from South Asia with high overall
preterm birth rates of 14 to 20%, but low proportions
(2%) of extremely preterm births (<28 weeks) compared
to the proportion from pooled datasets from developed
countries (5.3%). In addition, even where care is offered to
these very preterm babies, intensive care may be rationed
(MRC PPIP Users and the Saving Babies Technical Task
Team, 2010; Miljeteig et al., 2010).
Other cultural and social factors that have been reported
to affect completeness of registration include provision
of maternity benefits for any birth after the registration
threshold, the need to pay burial costs for a registered
birth but not for a miscarriage and increased hospital
fees following a birth compared to a miscarriage (Lumley,
2003). In low-income settings, a live preterm birth may
be counted as a stillbirth due to perceived non-viability
or to “protect the mother” (Froen et al., 2009).
The def in i t ion of p re te rm b i r th focuses on l i ve -
born babies only. Counting all preterm bir ths, both
live and stil lbir ths, would be preferable to improve
Table 2.3: Gestational age methods, accuracy and limitations
Method Accuracy Details Availability/feasibility Limitations
Early ultrasound scan +/- 5 days if first trimester+/- 7 days after first trimester
Estimation of fetal crown-rump length +/- biparietal diameter / femur length between gestational age 6 – 18 weeks
Ultrasound not always available in low-income settings and rarely done in first trimester
May be less accurate if fetal malformation, severe growth restriction or maternal obesity
Fundal Height ~ +/- 3 weeks Distance from symphysis pubis to fundus measured with a tape measure
Feasible and low cost In some studies similar accuracy to LMP Potential use with other variables to estimate GA when no other information available
Last menstrual period ~ +/- 14 days Women’s recall of the date of the first day of her last menstrual period
Most widely used Lower accuracy in settings with low literacy. Affected by variation in ovulation and also by breastfeeding. Digit preference
Birthweight as a surrogate of gestational age
More sensitive/specific at lower gestational age e.g. <1500 g most babies are preterm
Birthweight measured for around half of the world’s births
Requires scales and skill. Digit preference
Newborn examination ~ +/- 13 days for Dubowitz, higher range for all others
Validated scores using external +/or neurological examination of the newborn e.g. Parkin, Finnstrom, Ballard and Dubowitz scores
Mainly specialist use so far. More accurate with neurological criteria which require considerable skill. Potential wider use for simpler scoring systems
Accuracy dependant on complexity of score and skill of examiner. Training and ongoing quality control required to maintain accuracy
Best obstetric estimate Around +/- 10 days (between ultrasound and newborn examination)
Uses an algorithm to estimate gestational age based on best information available
Commonly used in high-income settings
Various algorithms in use, not standardized
Adapted from Parker, Lawn and Stanton (unpublished Master’s thesis)
The Global Action Report on Preterm Birth24
Preterm Birth Rate
To compare preterm birth estimates across countries, the methods used to produce estimates need to be comparable across countries, otherwise one is not comparing like-with-like. The process is complicated by having only limited data for the majority of countries (the exception being primarily developed countries), from definitions of preterm births that may vary across countries and data sources, and from the need to develop a statistical model to account for all these issues.
InputsPreterm birth rate data were identified through a systematic search of online databases, National Statistical Offices and Ministry of Health data and assessed according to pre-specified inclusion criteria. National Registries (563 data points from 51 countries), surveys (13 Reproductive Health Surveys from 8 countries), and other studies identified through systematic searches (162 datapoints from 40 countries) were included. Preliminary data with methods and identified inputs were sent to countries as per WHO’s country consultation process. Additional data points identified at this stage were included for the final analysis.
Statistical modellingFor 13 countries with data available using a consistent definition for most years 1990 – 2010, a model using the country’s own data only was used to estimate the preterm birth rates. Two statistical models were developed to estimate for all other countries, one to estimate for MDG regions “Developed regions” and “Latin America and the Caribbean” (Model I), and the other to estimate for all other regions of the world (Model II). Each model included a set of predictors or factors associated with preterm birth rate and was used to estimate for the countries in the model. Uncertainty ranges were estimated for all countries:
Model I was developed for 65 countries based on a total of 547 data inputs. Most of these countries had reported national data and data for time trends. The model included the following predictors: log LBW rate, mean maternal BMI, year, and also data variables data source, method of gestational age assessment and denominator (singleton or all births).
Model II was developed for 106 countries based on a total of 191 data inputs, in most cases population data. The model included the following predictors; log LBW rate, malaria endemicity, female literacy rate, and also data variables data source, denominator (singleton or all births) and method of gestational age assessment.
Gestational age subgroupsWe reviewed all data that separate preterm births to gestational age subgroups: extremely preterm (<28 weeks), very preterm (28 to <32 weeks), moderate preterm (32 to <37 weeks). The distribution was remarkably similar across the 345 data points from 41 countries in the period 1990 to 2010 (Table 2.4), which suggests a biological basis. There was no evidence of differences between regions or a change in the distribution over time. Given this remarkable consistency, we applied the proportions to the estimates for 2010 for all countries without their own data for these subgroups.
Limitations
Table 2.4: Distribution of preterm birth according to gestational age subgroup based on meta-analysis of 345 datapoints from 41 countries (n= 131,296,785 live births)
Preterm birth grouping Gestational ageProportion of all <37 weeks
(%)Lower 95%
uncertainty interval Higher 95%
uncertainty interval (%)
Extremely preterm <28 weeks 5.2% 5.1% 5.3%
Very preterm 28-<32 weeks 10.4% 10.3% 10.5%
Moderate or Late 32-36 weeks 84.3% 84.1% 84.5%
For 85 countries the systematic searches found no data on the rate of preterm birth. Few population-based data reporting preterm birth rates were identified for developing countries. Estimates for developing countries have relied on modeling using data from sub-national or facility based studies when available. These may not be representative of the population. For the Model II countries, time trend information was generally not available so trends in preterm birth rate were only estimated for countries with more consistent data over time, including 65 countries from Latin America and Caribbean, and from “Developed region”, but excluding countries with fewer than 10,000 live births in 2010.
World Health Organization estimates of preterm birth rates
Source: Blencowe et al. National, regional and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications
Box 2.1: Overview of estimation methods for national, regional and global preterm birth rates
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comparability especially given stillbirth/livebirth mis-
classification. An increasing proportion of all preterm
infants born will be stillborn with decreasing gesta-
tional age. The pathophysiology is similar for live and
stillbirths; thus, for the true public health burden, it is
essential to count both preterm babies born alive and
all stillbirths (Golenberg et al., 2012).
Until these classification differences based on method
(Table 2.3), lower gestational age cut-offs for registration
of preterm birth, the use of singleton versus all births
(including multiples), the inclusion of live births versus
total births (including live and stillbirths) and case ascer-
tainment have been resolved, caution needs to be applied
when interpreting regional and temporal variations in
preterm birth rates.
Using the data for actionPreterm birth rates — where, and when?
Global, regional and national variation of preterm birth for the year 2010 New WHO estimates of global rates of preterm births (see
Box 2.1 for methodology) indicate that of the 135 million
live births worldwide in 2010, about 15 million babies were
born too early, representing a preterm birth rate of 11.1%
(Blencowe et al., 2012). Over 60% of preterm births occurred
in sub-Saharan Africa and
South Asia where 9.1 mil-
lion births (12.8%) annu-
ally are estimated to be
preterm (Figure 2.3). The
high absolute number of
preterm births in Africa
and Asia are related, in
part, to high fertility and
the large number of births
in those two regions in
compar ison to othe r
parts of the world.
The variation in the rate
of preterm birth among
regions and countries
is substantial and yield
a di f ferent p icture to
other conditions in that
s o m e h i g h - i n c o m e
countries have very high
rates. Rates are highest
0
1000
2000
3000
4000
5000
6000
Northern Africa & Western
AsiaTotal number of births in
region (thousands)% preterm
Nu
mb
er o
f p
rete
rm b
irth
s (t
ho
usa
nd
s)
Latin America
& the Caribbean
Developed Central & Eastern
Asia
South-Eastern Asia &
Oceania
Sub-Saharan
Africa
South Asia
n=8,4008.9%
n=10,8008.6%
n=14,3008.6%
n=19,1007.4%
n=11,20013.5%
n=32,10012.3%
n=38,70013.3%
Preterm births <28 weeks
Preterm births 28 to <32 weeks
Preterm 32 to <37 weeks
Figure 2.3: Preterm births by gestational age and region for year 2010
Based on Millennium Development Goal regions. Source: Blencowe et al National, regional and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications
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The Global Action Report on Preterm Birth26
on average for low-income countries (11.8%), followed by
lower middle-income countries (11.3%) and lowest for upper
middle- and high-income countries (9.4% and 9.3%). However,
relatively high preterm birth rates are seen in many individual
high-income countries where they contribute substantially to
neonatal mortality and morbidity. Of the 1.2 million preterm
births estimated to occur in high-income regions, more than
0.5 million (42%) occur in the United States. The highest
rates by Millennium Development Goal Regions (“Millennium
Development Indicators: World and regional groupings,”Barker,
1983) are found in Southeastern and South Asia where 13.4%
of all live births are estimated to be preterm (Figure 2.3).
The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoeveron the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. © WHO 2012. All rights reserved.
Data Source: World Health OrganizationMap Production: Public Health Informationand Geographic Information Systems (GIS)World Health Organization
0 2,500 5,000 kilometers1,500
Preterm birth rate, year 2010<10%
10 - <15%
15% or more
Data not available
Not applicable
11 countries with preterm birth rates over 15% by rank:
1. Malawi
2. Congo
3. Comoros
4. Zimbabwe
5. Equatorial Guinea
6. Mozambique
7. Gabon
8. Pakistan
9. Indonesia
10. Mauritania
11. Botswana
Figure 2.4: Estimates rates of preterm birth in 2010
Source: Blencowe et al National, regional and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications .Note: rates by country are available on the accompanying wall chart. Not applicable= non WHO Members State
Figure 2.5: Estimated numbers of preterm births in 2010
Source: Blencowe et al National, regional and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications.Note: preterm birth numbers by country are available on the accompanying wall chart.Not applicable= non WHO Members State
The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoeveron the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. © WHO 2012. All rights reserved.
Data Source: World Health OrganizationMap Production: Public Health Informationand Geographic Information Systems (GIS)World Health Organization
0 2,500 5,000 kilometers1,500
10 countriesaccount for 60% of the world’s preterm births by rank:1. India2. China3. Nigeria4. Pakistan5. Indonesia6. United States of America7. Bangladesh8. Philippines9. Dem. Rep. of Congo10. Brazil
Number of preterm births,year 2010
<5 0005 000 - < 10 00010 000 - < 50 00050 000 - < 100 000100 000 - < 250 000250 000 or more
Data not availableNot applicable
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The uncertainty ranges in Figure 2.3 are indicative of
another problem — the huge data gaps for many regions of
the world. Although these data gaps are particularly great
for Africa and Asia, there also are gaps in data from high-
income countries. While data on preterm birth-associated
mortality are lacking in these settings, worldwide there are
almost no data currently on acute morbidities or long-term
impairment associated with prematurity, thus preventing
even the most basic assessments of service needs.
The maps in Figures 2.4 and 2.5 depict preterm birth rates
and the absolute numbers of preterm birth in 2010 by coun-
try. Estimated rates vary from around 5 in several Northern
European countries to 18.1% in Malawi. The estimated
preterm birth rate is less than 10% in 88 countries, whilst 11
countries have estimated rates of 15% or more (Figure 2.4). The
10 countries with the highest numbers of estimated preterm
births are India, China, Nigeria, Pakistan, Indonesia, United
States, Bangladesh, the Philippines, Democratic Republic of
the Congo and Brazil (Figure 2.5). These 10 countries account
for 60% of all preterm births worldwide.
Mortality rates increase with decreasing gestational age,
and babies who are both preterm and small for gestational
age are at even higher risk (Qiu et al., 2011). Babies born
at less than 32 weeks represent about 16% of all preterm
births (Box 6.1). Across all regions, mortality and morbidity
are highest among those babies although improvements in
medical care have led to improved survival and long-term
outcomes among very and extremely preterm babies in
high-income countries (Saigal and Doyle, 2008). In 1990,
around 60% of babies born at less than 28 weeks gesta-
tion survived in high-income settings, with approximately
two-thirds surviving without impairment (Mohangoo et al.,
2011). In these high-income countries, almost 95% of those
born at 28 to 32 weeks survive, with more than 90% surviv-
ing without impairment. In contrast, in many low-income
countries, only 30% of those born at 28 to 32 weeks survive,
with almost all those born at <28 weeks dying in the first few
days of life. In all settings,
these very or extremely
preterm babies account
for the majority of deaths,
especially in low-income
count r ies where even
simple care is lacking (see
Chapter 5).
Preterm births time trends 1990 to 2010Annual national preterm
b i r th ra tes were es t i -
mated for 65 countries in
Europe, the Americas and
Australasia with more than
10,000 live births in 2010.
These regions include
9
8
7
6
5
4
3
2
1
0
Year1990 1995 2000 2005 2010 2015 2020 2025
1 800
1 850
1 900
1 950
2 000
2 050
2 100
2 150
2 200
2 250
2 300
Pre
term
bir
th r
ate
(% o
f liv
e b
irth
s)
Num
ber
of
pre
term
bir
ths
(1 0
00’s
)
Figure 2.6: Time trends in preterm birth rate for regions with adequate data (Developed, Latin America and Caribbean) projecting to 2025 assuming the average annual rate of change from 2005 to 2010 is maintained
Based on Millennium Development Goal regions Source: Blencowe et al National, regional and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications
Photo: Bill & Melinda Gates Foundation/Frederic Courbet
The Global Action Report on Preterm Birth28
almost all the countries with national reported time series.
The absolute numbers and rates from 1990 to 2010 for
these countries suggest an increasing burden of preterm
birth (Figure 2.6). Despite a reduction in the number of live
births, the estimated number of preterm births in these
countries increased from 2.0 million in 1990 to nearly 2.2
million in 2010.
Only three countries, Croatia, Ecuador and Estonia, had
estimated reductions in preterm birth rates from 1990 to
2010. Fourteen countries had stable preterm birth rates
(<0.5% annual change in preterm birth rates). In all other
countries, the preterm birth rate was estimated to be the
same or greater in 2010 than in 1990.
An increase in the proportion of preterm births occurring at 32
to <37 weeks (late and moderate preterm [LAMP]) has been
reported over the past decades in some countries (Davidoff
et al., 2006). For countries with available data in this exercise,
there was no strong evidence of a change in the proportion of
all preterm births that were LAMP from 1990 to 2010.
Caution is required in interpreting preterm estimates from
many low- and middle-income countries where significant
data gaps exist and modeling relies on reported figures
from sub-national or facility-based studies which may
not be representative of the population. Preterm birth rate
trends for low- and middle-income countries suggest an
increase in some countries (e.g., China) and some regions
(e.g., South Asia) but given changes in the data type and the
measurement of gestational age, these remain uncertain.
Priority policy and program actions based on the dataIn 2010, approximately 15 million babies were born pre-
term, and more than 1 million died due to complications
in the first month of life, more from indirect effects, and
millions have a lifetime of impairment. The burden of pre-
term birth is highest in low-income countries, particularly
those in South Asia. Yet unlike many other global health
issues, preterm birth is truly a global problem with a high
burden being found in high-income countries as well (e.g.
the United States where almost 1 in 8 babies is born too
soon). However, while the risk of preterm birth is high for
both the poorest and the richest countries, there exists
a major survival gap in some regions for babies who are
preterm. In high-income settings, half of babies born at
24 weeks may survive, but in low-income settings half of
babies born at 32 weeks still die due to a lack of basic
care (see Chapter 5).
Preterm birth rates appear to be increasing in most of the
countries where data are available. Some of this increase
may be accounted for by improved registration of the most
preterm babies associated with increased viability and by
improved gestational assessment, with change to near
universal ultrasound for dating pregnancies in these set-
tings. It may, however, represent a true increase. Possible
reasons for this include increases in maternal age, access
to infertility treatment, multiple pregnancies and underlying
health problems in the mother, especially with increasing
age of pregnancy and changes in obstetric practices with
an increase in provider-initiated preterm births in moderate
and late preterm infants who would not have otherwise been
born preterm (Joseph et al., 2002). In the 1980s and 1990s,
the increases seen in many high-income countries were
attributed to higher multiple gestation and preterm birth
rates amongst assisted conceptions after treatment for
sub-fertility. Recent changes in policies limiting the number
of embryos that can be implanted have led to a reduction
in preterm births due to assisted fertility treatments in
many countries (Mohangoo et al., 2011). However, in many
The two big priorities from the data are firstly to close the survival gap for preterm babies in lower-income countries by implementing improved
obstetric and newborn care, and secondly to develop innovative solutions to prevent preterm birth all around the world.
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middle-income regions with newer, relatively unregulated
assisted fertility services, a similar increase may be seen if
policies to counteract this are not introduced and adhered
to. A reduction in preterm birth was reported from the 1960s
to 1980s in a few countries (e.g. Finland, France, Scotland),
and this was attributed, in part, to improved socioeconomic
factors and antenatal care. For the majority of countries
in low- and middle-income regions, it is not possible to
estimate trends in preterm birth over time as there are not
sufficient data to provide reliable evidence of a time trend
for preterm birth overall. Some countries in some regions
(e.g. South and Eastern Asia) have data suggesting possible
increases in preterm birth rates over time, but this may
represent measurement artifact due to increases in data
and data reliability.
Distinguishing spontaneous and provider-initiated preterm
birth is of importance to programs aiming to reduce pre-
term birth. For spontaneous preterm births, the underly-
ing causes need to be understood and addressed (see
Chapters 3 and 4), while in the case of provider-initiated
preterm births both the underlying conditions (e.g. pre-
eclampsia) and obstetric policies and practices require
assessment and to be addressed.
The proportion of neonatal deaths attributed to preterm
births is inversely related to neonatal mortality rates,
because in countries with very high neonatal mortality, more
deaths occur due to infections such as sepsis, pneumonia,
diarrhea and tetanus as well as to intrapartum-related “birth
asphyxia” (Lawn et al., 2005). However, although the propor-
tion of deaths due to preterm birth is lower in low-income
countries than in high-income countries, the cause-specific
rates are much higher in low- and middle-income than in
high-income countries. For example, in Afghanistan and
Somalia, the estimated cause-specific rate for neonatal
deaths directly due to preterm birth is 16 per 1,000 com-
pared to Japan, Norway and Sweden where it is under 0.5
per 1,000. This is due to the lack of even simple care for
premature babies resulting in a major survival gap for babies
depending on where they are born (see Chapter 5).
Preterm birth can result in a range of long-term compli-
cations in survivors, with the frequency and severity of
adverse outcomes rising with decreasing gestational age
and decreasing quality of care (Table 2.1). Most babies
born at less than 28 weeks need neonatal intensive care
services to survive, and most babies 28 to 32 weeks will
need special newborn care at a minimum. The availability
and quality of these services are not yet well established
in many low- and middle-income countries. Many middle-
income countries, currently scaling up neonatal intensive
care, are just beginning to experience these long-term
consequences in survivors. These effects are most marked
amongst survivors born extremely preterm; however, there
is increasing evidence that all premature babies regardless
of gestational age are at increased risk. The vast majority
(84%) of all preterm births occur at 32 to 36 weeks. Most
of these infants will survive with adequate supportive care
and without needing neonatal intensive care. However, even
babies born at 34 to 36 weeks have been shown to have an
increased risk of neonatal and infant death when compared
with those born at term and contribute importantly to overall
infant deaths (Kramer et al., 2000). Babies born at 34 to
<37 weeks also experience increased rates of short-term
morbidity associated with prematurity (e.g., respiratory
“The true costs of prematurity, especially on a long-term global level, are poorly understood and likely to be grossly underestimated.” (Simmons et al., 2010).
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The Global Action Report on Preterm Birth30
distress and intraventricular hemorrhage) than their peers
born at term (Femitha and Bhat, 2011; Escobar et al., 2006;
Teune et al., 2011). In the longer term, they have worse
neurodevelopmental and school performance outcomes
and increased risk of cerebral palsy (Quigley et al., 2012;
Woythaler et al., 2011). On a global level, given their relatively
larger numbers, babies born at 34 to 36 weeks are likely
to have the greatest public health impact and to be of the
most importance in the planning of services (e.g., training
community health workers in Kangaroo Mother Care (KMC),
essential newborn care and special care of the moderately
preterm baby) (see Chapter 5).
We have highlighted the differences in preterm birth rates
among countries, but marked disparities are also present
within countries. For example, in the United States in 2009,
reported preterm birth rates were as high as 17.5% in black
Americans, compared to just 10.9% in white Americans,
with rates varying from around 11 to 12% in those 20 to 35
years of age to more than 15% in those under age 17 or over
40 (Martin et al., 2011). Disparities within countries need to
be better understood in order to identify high-risk groups
and improve care.
The economic costs of preterm birth are large in terms of the
immediate neonatal intensive care and ongoing long-term
complex health needs frequently experienced. These costs,
in addition, are likely to rise as premature babies increas-
ingly survive at earlier gestational ages in all regions. This
survival also will result in the increased need for special
education services and associated costs that will place an
additional burden on affected families and the communi-
ties in which they live (Petrou et al., 2011). An increased
awareness of the long-term consequences of preterm birth
(at all gestational ages) is required to fashion policies to
support these survivors and their families as part of a more
generalized improvement in quality of care for those with
disabilities in any given country. In many middle-income
countries, preterm birth is an important cause of disability.
For example, a third of all children under 10 in schools for the
visually impaired in Vietnam and more than 40% of under-5’s
in similar schools in Mexico have blindness secondary to
Table 2.5: Actions to improve national preterm birth rate data
Definition consistency
Consensus on definition of preterm birth for international comparison, specifying gestational age
Numerator (number of preterm births)Simplified, lower cost, consistent measures of gestational age (GA)Widespread use and recording of GA
Consistent inclusion of all live births of all gestations or weight, and noting if singleton or multiple births and noting the proportion that are under 500 g/22 weeks and under 1,000 g/28 weeks for international comparison Also record all stillbirths from 500 g/22 weeks and 1,000 g/28 weeks (whilst collecting by other national definition for stillbirth if different e.g., 20 weeks in United States)
Denominator (number of births)Consistent measurement of all live births of all gestations noting if less than 22 weeks and if singleton or multiple birthsAlso record all stillbirths
Actions to improve the data Focus on capture and consistency: Gestational age and birthweight recording for all births
Improve reporting of neonatal cause of death with preterm as direct cause and as risk factor (counting deaths of preterm babies who die from other causes)
Collection of impairment data e.g., cerebral palsy and retinopathy of prematurity (ROP) rates according to a basic minimum dataset to increase consistency
For settings where additional capacity available:Improve measurement e.g. gestational age assessment using early, high-quality ultrasound scan, development and refinement of improved gestational age assessment tools for use in low- resource settings
Increase the granularity of the data: Record if provider-initiated, e.g., cesarean birth, or spontaneous and the basic phenotype, e.g. infection/relative contribution of each cause especially multiple births Improve the linkage of data to action: e.g., collating data by gender, socioeconomic status, ethnicity, subnational e.g. state
Impairment data according to a more comprehensive standard dataset
Data for action Set goals for national and global level for1. Reduction of deaths amongst preterm babies by 2025 2. Reduction of preterm birth rates by 2025
Regular reporting of preterm birth rates and preterm-specific mortality rates at national level and to global level to track against goals
Note that weight is the preferred measure in ICD 10, but GA is commonly used now. The weight and GA “equivalents” are approximate.
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retinopathy of prematurity (Limburg et al., 2012; Zepeda-
Romero et al., 2011).
Actions to improve the dataThe estimates in this report represent a major step forward
in terms of presenting the first-ever national preterm birth
estimates. However, action is required to improve the
availability and quality of data from many countries and
regions and, where data are being collected and analyzed,
to improve consistency among countries. These are vital
next steps to monitor the progress of policies and programs
aimed at reducing the large toll of preterm birth (Table 2.5).
Efforts in every country should be directed to increasing the
coverage and systematic recording of all preterm births in a
standard reporting format. Standardization of the definition
in terms of both the numerator (the number of preterm births)
and the denominator (the number of all births) is essential if
trends and rankings are to be truly comparable. Collecting
data on both live and stillbirths separately will allow further
quantification of the true burden, while data focusing on
live births only are required for monitoring of neonatal and
longer-term outcomes. These estimates indicate the large
burden amongst live-born babies. However, in developed
countries with available data, between 5 and 10% of all
preterm births are stillbirths, and the figure may be higher
in countries with lower levels of medically-induced preterm
birth. Distinguishing between live births and stillbirths may
vary depending on local policies, the availability of intensive
care and perceived viability of babies who are extremely
preterm. If estimates for live-born preterm babies were
linked to estimates for stillbirths, this would improve track-
ing among countries and over time. Achieving consensus
around the different types of preterm birth and comparable
case definitions, whilst challenging, are required where
resources allow to further understand the complex syn-
drome of preterm birth (Goldenberg et al., 2012).
In many low- and middle-income countries without wide-
scale vital registration, no nationally representative data are
available on rates of preterm birth. Substantial investment
and attention are required to improve vital registration sys-
tems and to account for all birth outcomes (Commission on
Information and Accountability, 2011). In the meantime, the
amount of population-based data available in high-burden
countries could be dramatically increased to better inform
future estimates and monitor time trends if data on preterm
birth rates were included in nationally representative sur-
veys such as the Demographic and Health Surveys (DHS)
and demographic surveillance sites, but this will require
developing and testing preterm-specific survey-based tools.
Innovation for simpler, low-cost, sensitive and specific tools
for assessing gestational age could improve both the cover-
age and quality of gestational age assessment. Data from
hospital-based information systems would also be helpful,
but potential selection and other biases must be taken into
account. Simpler standardized tools to assess acute and
long-term morbidities-associated preterm birth also are
critically important to inform program quality improvement
to reduce the proportion of survivors with preventable
impairment.
ConclusionThere are sufficient data to justify action now to reduce
this large burden of 15 million preterm births and more
than one million neonatal deaths. Innovative solutions to
prevent preterm birth and hence reduce preterm birth
rates all around the
world are urgently
needed. This also
requires strength-
ened data systems
to adequately track
trends in preterm
b i r th r a te s and
program effective-
ness. These efforts
must be coupled
with action now
t o i m p l e m e n t
improved antena-
tal, obstetric and
newborn care to
increase survival
and reduce disabil-
ity amongst those
born too soon.
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